The outer hair cell is thought to enhance the sensitivity of mammalian hearing. Its lateral wall consists of 3 concentric layers: an outermost plasma membrane, a cortical lattice, and an innermost collection of flattened membranes called the subsurface cisternae. The cytoplasm requires positive pressure for full expression of the outer hair cell's electromotility. Using micropipette aspiration, we investigated the mechanics of the guinea pig's outer hair cell lateral wall at room temperature (22 degrees C) and at the guinea pig's body temperature (39 degrees C). Although there was a 10% decrease in stiffness parameter with an increase from room to body temperature, the difference was not statistically significant; values ranged from 0.45 to 0.65 dyne/cm. With sufficient negative pressure, the cytoplasmic membrane is separated from the rest of the outer hair cell's lateral wall, a process that leads to vesiculation of the plasma membrane. Vesiculation occurs at a lower pressure than at body temperature. Our results demonstrate that the stiffness parameter of the outer hair cell lateral wall at body temperature is similar to that at room temperature. However, the plasma membrane's attachment to the cortical lattice is greatly altered by temperature. The decrease in strength of membrane attachment at body temperature may result from a change in membrane fluidity, making it more easy for membrane attachment sites to break free and permit vesiculation. Whether the tethering of the plasma membrane to the cortical lattice is lost under clinically pathologic conditions deserves future study.
Cost containment is at the forefront of responsible health care delivery. One way to decrease costs is to decrease hospital length of stay (LOS). Data are lacking on factors contributing to LOS in patients with head and neck cancer (HNC) undergoing fibular free-tissue reconstruction (FFTR) of head and neck defects.To identify factors contributing to increased LOS following FFTR of head and neck defects in patients with HNC using the American College of Surgeons National Surgical Quality Improvement Program (ACS NSQIP) methodology.Retrospective medical record review, with reference to the ACS NSQIP form, of 30 consecutive patients with HNC undergoing FFTR of head and neck defects in a single tertiary academic institution from July 2013 through June 2014. Data were collected on demographic and tumor characteristics, preoperative risk factors, operative variables, and postoperative adverse events.Factors associated with increased hospital LOS.Median LOS was 10 days (range, 8-31 days), and patients were divided into 2 groups (LOS, ≤ 10 days [n = 16]; and LOS, >10 days [n = 14]). There were no significant differences in demographics, tumor characteristics, or preoperative medical comorbidities between the 2 groups. Univariate analysis demonstrated that operative time, ventilator dependence, wound event, and altered mental status were associated with longer LOS. Multivariate analysis revealed significant association with LOS greater than 10 days for operative time of longer than 11 hours (odds ratio [OR], 7.26; 95% CI, 1.12-47.29; P = .04) and ventilator dependence for more than 48 hours postoperatively (OR, 12.05; 95% CI, 1.06-137.43; P = .045).Evaluated by the ACS NSQIP criteria, FFTR of head and neck defects in patients with HNC was associated with LOS longer than 10 days for procedures lasting longer than 11 hours and for patients who are ventilator dependent for more than 48 hours.
